21779686172 has 12 divisors (see below), whose sum is σ = 38151861720. Its totient is φ = 10879154256.

The previous prime is 21779686133. The next prime is 21779686177. The reversal of 21779686172 is 27168697712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21779686177) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2667623 + ... + 2675774.

It is an arithmetic number, because the mean of its divisors is an integer number (3179321810).

Almost surely, 2^21779686172 is an apocalyptic number.

It is an amenable number.

21779686172 is a deficient number, since it is larger than the sum of its proper divisors (16372175548).

21779686172 is a wasteful number, since it uses less digits than its factorization.

21779686172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5344420 (or 5344418 counting only the distinct ones).

The product of its digits is 3556224, while the sum is 56.

The spelling of 21779686172 in words is "twenty-one billion, seven hundred seventy-nine million, six hundred eighty-six thousand, one hundred seventy-two".